Such brushes are subject to a variety of requirements. Not only are they supposed to be capable of applying mascara as efficiently as possible, that is, in one stroke, if possible, without having to dip the mascara brush several times. Rather, they are also supposed to make it possible to curve the eyelashes in the sense of an upward curve (at the upper eyelid) or a downward curve (at the lower eyelid)—a treatment of the eyelashes referred to as “curling”.
Moreover, they are also supposed to be capable of exerting certain tensile forces on the eyelashes so that they are visually extended, which is also referred to by the term “extending/lengthening”.
Countless variations of mascara brushes have been proposed in the prior art which meet these requirements with different degrees of priority. In these cases, the focal point was so far directed primarily to finding a bristle covering whose bristles, depending on their specific diameter and their specific hardness, have exactly those different lengths that are optimal for reaching a good compromise in meeting the above-mentioned requirements.
Moreover, experiments with various bristle spacings were always carried out while trying to reach a good compromise in meeting the above-mentioned requirements.
Furthermore, the use of disc-shaped, rib-shaped or fin-shaped bodies that have a diameter considerably smaller than their length instead of conventional bristles was also already taken into consideration. However, the use of such massive bodies whose volume respectively exceed the volume of a single conventional bristle by several times also did not result in any decisive improvement, in particular also because the eyelashes are not distributed very well between these few large bodies which then constitute the bristle area, so that there is no sufficient separation.
Finally, it has also been proposed in practice that additional clamping organs separate from the bristles be used, which press the eyelashes from the outside against or onto the bristles, thus making it possible to grip the eyelashes in a plier-like manner for the purpose of curling or extending/lengthening in order to curve them or to more or less extend them in a desired manner.